1. Field of the Invention
The present invention relates to a process for regulating the growth of the microbial and/or bacterial flora, yeasts, molds and enterobacteria, that grow and flourish in the water circuits or processing streams in the papermaking industry.
2. Description of the Prior Art
Used paper and paperboard, generally designated "cellulosic recovery fibers," are today, as is wood, important raw materials in the papermaking industry. The recycling of such fibers is generally carried out in paper mills according to the following sequence:
The paper and fiberboard, recovered and stripped of any foreign body of the staple or plastics type, for example, are introduced into a pulper or disintegrator and therein dispersed in water. The resulting pulp, comminuted and then deflaked, is then subjected to a refining step, entailing swelling the cellulosic fibers by hydration. The actual production with initial formation of a sheet of paper is subsequently carried out on a filter cloth or wire with removal of water, drying and finally winding.
The paper production line hence includes a continuous water feed, the water being partially recycled, generally via a plurality of ancillary water circulation circuits.
The partial recycling of this water in the production line naturally promotes the growth of bacterial flora. This flora is undesirable since it causes slime formation.
In the papermaking industry, "slimes" are the chemical or biological deposits that occur in the production circuit. They can comprise fibers, carbonates or other inorganic fillers or bacteria. Upon detachment from the tanks or pipes in which they have accumulated, these slimes cause breaks in the paper and colored spots thereon. This results in frequent halts in the production line and a deterioration in working conditions.
At present, the solutions proposed for limiting slime formation employ chemical or, alternatively, biocidal disinfectants. These are generally organochlorine- and organobromine-based chemicals which effectively inhibit the growth of the contaminant flora.
However, by virtue of their chemical nature, these compounds are not entirely satisfactory.
For example, they are highly toxic and nonbiodegradable.
Their release, even partial, into the environment also presents serious ecological difficulties, and, more especially, creates a problem of purification of the contaminated water.
Finally, to attain effective inhibition of the bacterial flora, it is necessary to employ several biocides alternately, as well as increasingly greater amounts or doses thereof. It is apparent that the repeated introduction of such larger amounts aggravates the problem of pollution.
Consequently, the use of biocides for the treatment of bacterial flora is today highly suspect from an ecological standpoint and means for avoiding such use is a more than desirable goal.